Refrigeration compressor



Jan. 27, 1948. J. TOUBORG 435,3 0@

REFR I GERAT ION COMPRES SOR Filed' Deo. 18, 1943 a sheets-mi@ x :NVEN'TOR ATTORN Jan. 27, 1948. ]TOUBQRG REFRIGERATION COMPRESSOR Filed Deo. 1.8, 1943 3 Sheets-Sheet 2- JQTOUBO'RG v 2,435,108

REFRGERAT ION COMPRES SOR Jan. 27, 1948.

Filed Dec. 18, 1943 3 Sheets-Sheet 3 47 475 ad w- 7 u l j-'g. Q9

87 v F l @gs JOUZO v v Patentedy Jan. 27, 1.948

REFRIGERATION COMPRESSOR l Jens Touborg, Tecumseh, Mich., assigner to Tecumseh Refrigeration Sales and Engineering Company, Tecumseh, Mich., a corporation of Michigan Application December 18, 1943, Serial No. 514,813

1 This invention relates to an improved refrigeration compressor, wherein provision is made -for supercharging the suction gases, thereby enabling the machine to operate with high capacity and good emciency when supplied with gases at relaltively low suction pressures, as well as through out the ranges of operation heretofore considered as normal. Heretofore, the art has had compressors adaptled to be driven by fractionalhorsepower`motors and to handle enough refrigerant to meet the demands of most small r domestic installations, and to operate with good efficiency so long as the temperatures to be maintained were not too low.

When, however. it is desired to cool to say, zero degrees Fahrenheit or lower. the corresponding rarefaction of the expanded refrigerant curtails the weight of gas which can be handled per cycle, and thusleads to loss of capacity and low efficiency. Other ,complications with respect to machine performance, such as cylinder head clearance and valve action, are also encountered. Attempted correction of the disadvantages of oper- A11 claims. (cieco-5s) `l 2 the advantages to be derived from the adoption thereof, will be apparent from a perusal of the following description of a single lembodiment, illustrated in the accompanying drawings, wlierein:

Fig. 1 is a section through the compressor assembly, illustrating the same as embodied in a sealed or hermetic unit;

ation, by initially providing a larger machine, of

course imposes a higher initial cost `and I'coritinuing operating. charges, and therefore is not economically warranted. y

In order to solve this problem, the 'present invention provides for thesupercharging, or precompresslon of the suction gases, so that the unit weight of refrigerant handled by the main cylindervis high, despite theinitially low temperature and pressure, and moreover correlates the 'action between the pre-compression and final compression stage, so that the one stage is under suction while the other is under compression.

An improved mechanism for driving the pistons, of the Scotch yoke type, is also incorporated as one aspect of the invention, and such mechanism is moreover made to gove'rn the opening and closing of the admission and discharge ports through which the refrigerant flows. There is thereby provided acombined Scotch yoke and sleeve valve mechanism imparting to the motion cycle of the machine a smooth and harmonic action, and 'to the concomitant work cycle a high eliiciency. v

Suitable provision is made for adapting the compressor for encasement in a sealed housing, according-to the hermetic principle, for mounting the machine to safeguard against the developproviding an improved compressor, as the following specification will make clear.

The principles of the invention,

Il()v4 comprising a two-part casing II having upper head assembly, as

Fig. 2 is a bottom endview of the main shaft, showing the relative positions of the shaft, eccentric, and some of the gas and oil ports;

Fig. 3 is a longitudinal section taken on the line 3--3 of Fig. 2, showing the porting arrangement in the lower portion of the shaft;

Fig. 4 is a bottom plan` view of the compressor assembly, the casing being shown in section as indicated by the line 4--4 of Fig. 1:

Fig. 5 is a fragmentary view taken along the line 5--5 of Fig. 4, showing how the discharge conduit passes through the casing wall;

Figs.v 6, 7, and 8 are longitudinal sectional views taken through the piston, crosshead, and shaft assembly, at right angles to the section shown in Fig. l, and respectively illustrating successive positions of the parts; and

Fig. 9 is a plan view of the` piston and crossviewed from the sectionl line 9-9 of Fig. 1. f Y

Referring first to Fig. 1, the invention is shown asa hermetic or sealed refrigeration compressor,

and lower pressed sheet metal sections I2 and I3. in which is disposed a main casting I4 for mounting an electric driving motor I5, and a compressor assembly generally designated by the reference numeral I6. The main casting includes an upstanding annular ange Il into which is pressed the stator I8 of the motor, and al central upright bearing-boss 'I9 which receivesadrive shaft 2|, to the upper. end of which is secured the motor rotor 22. The hub 234 of the 'rotor is formed with a depending flange 24 which -overhangs the upper end of the bearing boss yI 9,'thereby to return oil to the lower shell half I3, Ifrom which it is supplied in a manner presently" to be described. y

The iiange I'l and bearing I9 are interconnected by horizontally .extending Webs 25, 'also shown in the lbottom plan view, Fig. 4, and from the` central portion of these webs there depends a cylinder block 26 for the compressor I6, Three suitably spaced bosses 21 are formed on the periphery of the main casting I4, in line'yvith the webs 25, for supporting the assembly Within the casing l I. Each boss 2l is adapted to register with a shelf ment -of noise and vibration, and for otherwise v tosetnenwith 23 welded within the lower shell section I3. and provided with a threaded post 23 onto which is screwed a supporting spring 3|. Each boss 21 is provided with a corresponding threaded post 32 which, however, is detachable, being secured from displacement after assembly by a set screw 33. The spring 3l nests snugly on the threads of the posts 23 and 32, thereby providing a. secure, but resilient connection which not only supports the motor and compressor assembly. but precludes the development oi' noise. The assembly may be readily effected by setting the posts and springs in the lower shell. then dropping the main casting assembly in place. taking up the set screws 33, and finally applying the upper shell section I2.

The upper shell section is also provided with a nanged band 35, which may be pressed in place and welded in position over the bosses 21 in slightly spaced relation thereto. The band 3l prevents the compressor assemblv from undue upward or lateral movement which would strain the springs 3|, eitherduring conditions of operation, or during shipment when the entire unit is apt to be upset. A bindingpost or electric connector 33 is also positioned in the casing, preferably in the lower portion, for supplying current to the motor through suitable wires 31.

The block 28 is formedwith two Aspaced and.

axially aligned apertures 4I and 42, respectively constituting the precompression or supercharg ing cylinder and the main working cylinder of the compressor assembly I3. The cylinder 4I is of greater diameter than the cylinder 42. and it is adapted to receive a reciprocable piston 43, formed with a piston rod 44 which extends to a yoke 4l, and thence to a piston rod 43 for the small piston 41, which reciprocates in the cylinder 42. The drive shaft 2I, rotatably mounted in the main bearing I 3. is formed with a depending axially offset cylindrical portion or eccentric 43, which passes through the yoke 43 and an interposed crosshead 49, to rest on a foot bearing l I secured to the bottom of the block 23. Mountted between the, yoke 45 and the foot bearing is a. counterweight 32. secured by a set screw 33, which serves to dampen vibrations while the machine is running.

The block 23 is, of course. made hollow between the two cylinders 4I and 42 to `provide a crankcase portion 54 in which the piston rods and connecting mechanism may be accommodated. The lower shell portion I3 is intended to receive a pool of oil which submerges the. foot bearing and lower end of the eccentric 43, and thereby supplies lubricant to the crankcase and the pistons directly. Oil is conveyed to the main bearing I3 by means of a duct 33 and a communicating branch duct 33 which is aligned with'an aperture B1 formed in the foot bearing lil. As shown in Figs. i. 2, and 3. the upper end of the duct Il communicates with a spiral groove 53 formed on the main section of the shaft 2 I which elevates the oil to the bearing for ultimate gravity return around the flange 24. This lubrication system is of a forced feed, centrifugal pump type. which is also described in mv prior Patent No. 2.274.943, patented March 3. 1942, It need not therefore be further discussed here. except tosay that the rotation of the shaft forces the oil up through the duct 35 and intn the groove 33, thereby to provide satisfactory lubrication.

The eccentric portion 43 of the drive shaft 2l passes through the crosshead 43. which in turn is positioned in the yoke 45. and in this manner provides a driving connection for the Simultaneous reciprocation of the pistons 43 and 41. As

portion 43 is axially oifset with respect to the rotative axis of the shaft 2i, and therefore it describes a circular path around the main shaft axis as the shaft revolves. As shown in Figs. 1

and 9, the yoke portion 43 is formed with a cylindrical bore II transversely disposed with respect to the axes of the pistons and the shaft. and this bore receives the crosshead 43, which is a cylindrical piece formed with a bore 32 which is aligned with the eccentric 43. A clearance slot I3 is cut at the top and bottom of the yoke 4l to accommodate relative motion between the yoke and eccentric, as best shown in Fig. 9. This ligure also shows how the pistons are integrally connected tothe yoke through the aligned piston rod portions 44 and 43.

Figs. 6, 1, and 8 show successive positions of the parts as the shaft 2| revolves under the influence of'the motorli. The motion will be described beginning with Fig. 6, wherein the large piston 43 is at the extreme right oi.' its which is bolted onto the casting portion 23 after the parts have been assembled. This position of` the piston 43 in its cylinder 4I will arbitrarily be assumed to be s. zero position, and it corresponds to the end of the pre-compression stroke, as hereinafter more fully explained in connection with the pumping arrangement. In like fashion, Fig. 6 therefore shows the small piston 41 at the extreme right, which in turn corresponds to the end of its suction stroke. Counterclockwise rotation of the shaft 2i and eccentric 43 will also be assumed.

As the eccentric 43 lrevolves, its periphery moves upwardly and to the left, since the fixed centerline of the shaft 2| is located along the line marked CLS." The upward motion therefore causes the crosshead 49 to move in the direction of the arrow in Fig. 6 for the first ninety degrees of rotation, when the parts assume the positions shown in Fig. 7. At this time, the piston 43 has been withdrawn part way from the headplate I4, and the piston 41 has moved part way to the left. The next ninety degrees of rotation causes the eccentric to be further displaced toward the left, thus causing the two pistons to move to the left as far as they will go. However, the thrust on the crosshead 43 is now in the opposite direction, causing it to move downward and again to the position shown in Fig. 6. It will be understood, of course, that after degrees rotation from Fig. 6. the pistons are shifted with respect to their cylinders.

This therefore corresponds to the end of the suction stroke of the big piston 43, and the end of the compression stroke of the piston 41. A further rotation of the eccentric 43 through an arc of'ninety degrees brings the parts to the position shown in Fig. 8, wherein it will be seen that the crosshead 43 has now moved downward,4

being unsatisfactory for practical use, when compared to the more commonly used forms of driving connections, and therefore' s ome reference will be made to features which have shown it' .ing at relatively low speeds.V These concepts are not indicated for a compressor of the type under discussion, since compactness of the parts and direct connection to the driving motor are desired. Moreover, the art has heretofore considered it expedient to mount the cylinders separately around their pistons, which presents a problem of alignment hardly compatible with the close tolerances demanded for an eilicient I small compressor.

angles by the axis of the crankcase portion 54 and the shaft` 2|. The yoke 45 is, moreover, so dimensioned that it has less length than the diameter of the large cylinder 4I. Accordingly, the entire integrated piston and yoke assembly may be assembled in the block by insertion from the left, or big end. Each piston now serves as an extended bearing for the other, and for its piston rod, thus providing adequate' bearing surface, and also maintaining the parts in the very close alignment which is readily obtained with modern shop methods.

The crosshead 49 is readily inserted in the yoke 45 after the pistons are positioned. The eccentric portion 48 of the shaft 2l, lwhile oifsetwith rev spect to the shaft axis, does not, however, project beyond the outer trace of the shaft, and hence this part may be dropped down through the bore of the bearing I9. By simply manipulating the parts, the eccentric may be inserted inthe bearing bore 62 of the crosshead, vuntil the lower end of the eccentric reaches the position in which it will be supported by the foot bearingl. The

counterweight 52 is thereafter applied and set,I

and the foot bearing is bolted on, thereby com pleting the assembly. In such construction, the

' axis of these cylinders being intercepted at right l within the band 35.

objections heretofore made to the Scotch yoke have been overcome.

In order to perform the work of compression of the refrigerant or other gas, it is desired to admit the relatively low density gas first to the larg'e cylinder 4I, thereafter transfer it to the small cylinder 42 for further compression, and then expel it to a discharge line communicating with the usual condenser and` other parts of the circuit. To this end, the'casing I2 is provided with an inlet' port 61 at its upper portion, which, as it may be assumed, is connected to the suction line of an evaporator contained in the refrigerating circuit. The main shaft 2i is axially bored to form a conduit 68, which is open at its upper end to the casing l l, thus providing free communication between the suction line and the shaft e bore.

The conduit 68 merges into a duct 69, formed in the eccentric 46, which duct extends down to the axis of the pistons, where it is intersected by an arcuate slot 1| formed ln the eccentric. The crosshead 49, at the same region, is formed with an arcuate slot 12 merging into the bearing bore 62, as shown in Figs. 6, 7, and 8. These slots are verse ports, one port 13 communicating with the slot 12, and the other port 14 being spaced therefrom and extending all the way through the crosshead. The port 13 is, at times, adapted to communicate with a duct 15 extending through the piston 43 and its rod 44, and the port 14 ls similarly adapted to communicate with or to be isolated from a duct 16, also formed in the large piston in spaced relation to the duct 15. The piston 41 and its rod 46 are formed with a duct 11 aligned with the duct-16, and thus adapted to be placed in communication therewith through the medium of the port 14. These passages respectively provide for admission and discharge of gas in the cylinder 4I, and admission to the cyl inder 42.

The head end of the cylinder 4I, as heretofore noted, is closed by the imperforate head plate 64.

The head end ,of the small cylinder 42 is covered by a plate 18, within which is mounted a springpressed discharge valve 19, which may be of the usual form for compressors of this nature. The end of the piston 41 carries a leaf valve 8l, which covers the duct 11, and is adapted to open in-- wardly when gas flows through the duct 11, and to close when the piston moves to the left on its compression stroke. The space between the discharge, valve 19 and the plate 18 communicates with a passage, not shown, to a muilier chamber 82 carried by the block 26 (see Fig. 4), from whence-the compressed gas flows into a discharge line 83.

As shown in Figs. l and 4, the discharge line 83 is taken upwardly within the casing Il, and ls` given several turns 84 around the fiange I4 and The line then is led out throughA the casing by a portion 85, as shown in Fig. 5, for connection to the condenser. The path of gas flow is. accordingly, into the casing Il through the inlet 61, thence to the conduit 68 in the shaft 2l, to the large cylinder 4I, and then to the small cylinder 42, through the discharge line 83 again within the casing, and finally out of the machine A fan 86 is secured to the upper end of the shaft 2i, to stir the incoming gases as they enter the' casing. The improvements just `described are concerned with the transfer of motor heat away from the apparatus, and modlfying the density of the gas entering the prevcompression or supercharging cylinder. The cold incoming gas conducts the motor heat to the `casing wall, where it may be dissipated, and also the suction gas is also separated and drops by gravity to the pool at the bottom of the casing.

Again referring to Figs. 6, 7, and 8, the work cycle is as follows, the heretofore described motion cycle being assumed. At the beginning of the cycle, Fig. 6, the crosshead 49 moves up- Wardly to place the port 13 in registry with the duct 15, and. at the same time, the slots 1| and same arc-the slot 'n as .t 7 v 12 are also in registry. The motion of the pistons being toward the left, gas is therefore inducted into the cylinder 4|. concurrently, the movement of the crosshead 4causes the port 14 to slide past the ducts-14 and 11 which are thereby cut on or-isolated. Suction now occurs in the cylin` der 4 I, while compression takes place in the cylinder 42the compressed gas being precluded from flowing back into the duct 11 by the valve Il, and being forced past the valve 1! when the pressure builds up to a suitable point. f The port 13 maintains communication with the duct 1I for the first 180 degrees of rotation (or substantially so as determined by the precise settings), thus inducting a full volume of gas into the cylinder 4| before the piston 43 begins its movement to .the right; At the 130 degree position, the port 1I is cut oi! from the duct 1I, and the port 14, whi'e still cut of! from the ducts Il and 11, is about` to open communication between them. The compression stroke of the piston 43 thereupon forces the volume of gas conand 11 and the port 14. shown in the figures (no appreciable lag being given to thek port 14) the compression ratio between the cylinder 4I and the cylinder 42 will be as the square of the diameters, the displacement of the pistons being the same. course, is subject to some modification and ad- Justment as various conditions warrant, but such a ratio, or approximately l:2.25, is suitable for the type of work herein specifically referred to.

Delivery of the pre-compressed or supercharged gas to the main compression cylinder 42 continues as the pistons move to the right through the second half of the cycle. When the pistons again move to the left, the enriched volume now contained in the small cylinder 42 is compressed in the usual manner-thus the action is made to be as though the machine were working on a gas of greater density. a

In examining into embodiments of the invention, it has been observed that there is lsome gain in efliciency if the ports and ducts through which the refrigerant flows are madeof vample This, of

s scope whereof is to be determined from their proper context.

I claim:

l. A compressor having a pair ofaligned cylinders, one of which is of greater diameter than the other, pistons reciprocably mounted in the cylinders and iixedly connected to 'each other, a Scotch vyoke including a crosshead interposed between the pistons, and valve means in the crosshead of said yoke for controlling the admission of fluid to said cylinders in timed relaregister periodically with said ducts as the pistons tained in the big cylinder through the ducts 18 i.

For the port settings size-such size, of course, being dependent upon the actual dimensions of the machine. It has also been found that the machine is quiet in operation, and that by comparison with :machines of the Asaine displacement, `it can maintain a higher capacity at low suction pressures, land also a high eiilciency in terms of thermal work per-vv v formed for a given electricalpower input. These improvements are obtained without resorting to a unit of greater size or horsepower requirement.

It will be seen that the present compressor in effect combines a supercharger withthe usual compression chamber, that there has been provided a. novel Scotch yoke and valve mechanism forcontrolling both the motion and work cycles of the machine, and that the invention offers,- other useful features adapted to machines of' this general class.

It is, of course, understood that while the invention has been described` with respect to a l specific embodiment, and the applicability thereof to the compression of refrigerating gas, the principles of the invention may be embodied in many other forms and adapted to other purposes, and that they are not limited to the precise details of the machine herein illustrated. Accordingly it is intended that the invention should be deemed to consist of the partsor combinations set forth inthe following claims, the

reciprocate, said port means admitting iluid to the larger of said cylinders and sequentially to the smallerof said cylinders upon the suction strokes of the pistons.

3. A compressor having'a pair of spaced cylinders, one of which is of greater diameter than the other, pistons reciprocably mounted in the cylinders and having piston rods extending therefrom, a drive shaft having an eccentric, a Scotch yoke connection between the eccentric and the piston rods, said yoke including a crosshead, fluid ducts formed in the piston rods and communieating with the cylinders, and ports formed in the' crosshead of the yoke adapted to admit iiuid to the larger cylinder through one of said ducts and from the larger cylinder to the smaller cylinder through theother of said ducts, said ports being so spaced as to effect said admissions assequential operations occurring in timed rela-i tion to the suction strokes of the pistons as they are reciprocated through the yoke.

4. A machine having a pair of spaced aligned cylinders. one of which is of greater diameter than the other, pistons mounted in said cylinders for reciprocatory movement, mechanism for reciprocating the pistonsA and concurrently admitting fluid to the cylinders comprising a yoke interposed between the pistons and fixedly connected thereto, a crosshead reciprocably mounted in the yoke transverse'y of the axis o'i the pistons, an

eccentric engaging the crosshead for reciprocat,

ing the same in the yoke and the pistons in the cylinders, a port formed in-the crosshead and a duct formed in one of the pistons, said port and duct being adapted to register during one phase of a complete cycle of operation, a second port formed in the crosshead, said second port being adapted to register during another phase with additional ducts formed in each of said pistons, means formed in the eccentric for connecting the rst named port to a region extraneous of the pistons and cylinders, valve means independent ofthe said ports and ducts for'connecting one of said cylinders to a region extraneous of the pistons, said'ports and ducts being s'o related with respect to each other and the displacement of the crosshead as to connect the cylinders for fluid communication during one phase of reciprocal motion of the pistons, and to-isolate the cylinders during a successive phase. v

5.-In a compressor having a cylinder and a piston reciprocably mounted in the cylinder. a Scotch yoke connection attached to the piston to reciprocate the same, said yoke including a crosshead, inlet and discharge ducts for the cylinder formed in the piston and extending from the cylinder to the yoke, and sleeve valve ports formed in the crosshead of the yoke and adapted successively to open and cut off said ducts as the crosshead reciprocates in timed relation to the piston.

6. In a compressor having a cylinder and a piston reciprocably mounted in the cylinder, a cylindrical yoke formed on the crankcase end of the piston, said yoke being transverse to the direction of reciprocation, a cylindrical crosshead reciprocably mounted in the yoke, a bearing in the crosshead having an axis disposed transversely to the direction of reciprocation and the axis of the crosshead, an eccentric rotatably mounted in the bearing, slots formed on the eccentric and in the bearing adapted to register with each other during one phase of a cycle of operation, spaced ducts formed in the piston and extending from the head end thereof to the yoke, and ports formed in the crosshead adapted to communicate with said ducts during successive phases of a cycle of operation, one of said ports communicating with the crosshead slot, and a conduit communicating with the slot in the eccentric, whereby the crosshead serves as a sleeve valve controlling admission and discharge from the cylinder concurrently to ef fecting reciprocation of the piston.

7. In a compressor having a, cylinder anda piston reciprocably mounted in the cylinder, a cylindrical yoke formed on the crankcase end of the piston and disposed transversely to the direction of reciprocation, a cylindrical crosshead reciprocably mounted in the yoke, an eccentric rota*- ably mounted in the crosshead, the axis of the eccentric being transverse to the axes of the yoke and the cylinder, a fluid duct formed in the piston and extending from the head end thereof to the crosshead, and a port formed in the Wall of the crosshead and adapted to register with and to be cut off from the duct during successive phases of movement of the piston and crosshead.

8. In a compressor having a cylinder and a piston reciprocably mounted in the cylinder, a drive shaft disposed at substantially right angles to the axis of the cylinder, a conduit formed in the shalt and having one open end, an eccentric formed on the shaft and extending adjacent the cylinder axis, a crosshead in which the eccentric is rotatably mounted and a yoke engaging and guiding the crosshead for reciprocable movement, said yoke being connected to the crankcase end of the piston, a duct formed in the piston and extending from the head end thereof to the yoke, and a port formed in the crosshead and adapted periodically to provide communication between the conduit and the duct as the crosshead and piston are reciprocated by rotation of the shaft.

9. In a machine of the character described, a cylinder block having a, pair of spaced and axially aligned cylinders, one of which is of greater diameter than the other, means providing a removable cover plate for the head end of the larger cylinder, a cavity formed in the ,block to provide a crankcase portion between the cylinders, a drive shaft disposed transversely to the axis of the cylinders, said drive shaft having an eccentric portion extending across said axis, a crosshead positioned around the eccentric and disposed transversely with respect thereto, a yoke surrounding the crosshead, pistons positioned in the cylinders and connected to the yoke, the diameter and.

length of the yoke being such that it may pass through the larger cylinder, the eccentric being such that its outer trace lies within the trace of the shaft. y

10. In a machine of the class described, a pair of spaced and aligned cylinders, one of which is of greater diameter thanl the other, a drive shaft, and a pair of pistons adapted to be reciprocably mounted in the cylinders and driven by the shaft, said pistons each having integral piston rods extending coaxially from their crankcase ends and merging into an integrally formed yoke having a cylindrical bore disposed transversely of the axis of the pistons, a cylindrical crosshead slid-ably mounted in the bore, diametrically opposed slots formed in the Wall of the yoke in spaced relation to the piston rods, said slots being elongated, a bearing bore formed inthe crosshead and positioned transversely to the axis of the pistons and the crosshead, a driving eccentric rotatably mounted in the bearing bore-andconnected to the drive shaft, the length of the yoke being less than the diameter of the larger piston,` vand the lots being of such area as to accommodate the circular movement of the eccentric'with respect to the center of the driving shaft.

11. In a machine of the class described, a cylinder block having a pair of spaced depending portions mutually interconnected by an overlying web, cylinders formed in the depending portions, said cylinders having a common longitudinal axis, a bearing portion disposed in the web and having an axis substantially perpendicular to the cylinder axis and intersecting the same, pistons reciprocably mounted in the cylinders, said pistons being formed with rods extending from the crankcase ends thereof and between the webs, a yoke mutually connected to the rods, said yoke being disposed transversely to the axes of the cylinders and the bearing portion, a crosshead reciprocably mounted in the yoke, a drive shaft mounted in the bearing portion and having an offset depending eccentric depending therefrom and rotatably mounted in the crosshead, a detachable foot bearing positioned below the web and extending between the depending portions of said block at the lower ends thereof, said foot bearing being adapted to support the end of the eccentric, a counterweight mounted on the eccentric between said foot bearing and the yoke, and cylinder head plates mounted respectively on the depending portions of the block to cover the head ends of the cylinders.

JEN S TOUBORG.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,523,790 Pedersen Jan. 20, 1925 1,960,035 Warren May 22, 1934 2,101,881 Terry Dec. 14, 1937 2,130,276 Hornaday Sept. 13, 1938 2,130,862 Steenstrup Sept. 20, 1938 2,199,414 Patrignani May 7, 1940 2,219,199 Renner Oct. 22, 1940 2,256,926 Maniscalco Sept. 23, 1941 2,285,754 Money June 9, 1942 

